Vitamin D and Its Role in Diabetes

Vitamin D, otherwise known as the “sunshine vitamin,” is vital for bone health but may soon be regarded as an important marker of health similar to cholesterol and blood pressure. Over the last few decades, scientists have looked past the skeletal support this micronutrient offers and are discovering that vitamin D may play a vital role in insulin, glucose, and inflammation regulation as well as potentially being a warning sign for different cardiovascular and endocrine diseases — including type 2 diabetes.

So What Exactly Is Vitamin D?

Vitamins are chemicals the body needs to function properly and are required to maintain good health. There are two main categories of vitamins: water soluble and fat soluble vitamins.

Fat Soluble Vitamins

Water Soluble Vitamins

Vitamin A (retinol)

B1 Thiamine

B7 Biotin

Vitamin D

B2 Riboflavin

B9 Folate

Vitamin E

B3 Naicin

B12 Cobalamin

K

B5 Pantothenic acid

C Ascorbic acid

B6 Pyridoxine

As seen in the table above, water-soluble vitamins like vitamin B and vitamin C are generally excreted and can be replenished daily with little to no worry about toxicity for most people. Fat-soluble vitamins like vitamin D are stored in the liver and fatty tissue and are not always required daily by everyone (depending on your nutritional status).

Excessive amounts of vitamin D and other fat-soluble vitamins can be toxic, but being deficient in one of these vitamins can cause numerous other health problems as well.

Vitamin D is unlike any other micronutrient in that the body can produce its own from sunlight whereas most other vitamins are acquired by the foods you eat.

3 Ways to Get Vitamin D

The three main ways to get vitamin D are through sun exposure, vitamin D supplementation, and dietary intake.

Sun/UVB

The best way to get vitamin D is to get some sun exposure. After all, it is the “sunshine vitamin.” The human body was designed to convert the ultraviolet (UVB) rays from sunlight into vitamin D– the same UVB rays that can cause sunburn. Vitamin D is considered “inactive” until sunlight causes a chemical reaction producing vitamin D that is then sent throughout the body to the corresponding tissues.

The Vitamin D Council Organisation recommends little bits of sun exposure just shy of causing a skin burn to optimally produce enough vitamin D. The most vitamin D is produced in the middle of the day, with bigger parts of your body exposed like your back or chest– especially if you live closer to the equator.

Supplementation

Some people are at a greater disadvantage in producing optimal vitamin D levels from the sun including those who:

Have a dark skin complexion

Live farther away from the equator

Are overweight

Are older

Stay covered up in the sun

For those people who can’t regularly achieve optimal vitamin D levels through sun exposure alone, vitamin D supplementation may be necessary. Below is a list of the recommended daily allowance and upper limits of vitamin D supplementation from the National Institute of Health

Dietary Intake

Dietary intake is the least effective way to get adequate amounts of vitamin d that the body needs but can still be helpful. Certain foods higher in vitamin d include:

Cod liver oil

Fatty fish like salmon or trout

Dairy

Eggs

Tofu

Vitamin D is simply not abundant in food sources and does not serve as a reliable source so be sure to still get your sun exposure or talk to your doctor about supplementation.

Why Vitamin D Is So Important

Researchers discovered decades ago that vitamin D aided in bone strength and bone health as calcium and phosphorus, minerals needed for healthy bones, require the presence of vitamin D in order to be absorbed. A combined analysis of 12 fracture prevention trials that included more than 40,000 elderly people (mostly women) found that high intakes of vitamin D supplements reduced hip and non-spine fractures by 20 percent.1

With the benefits of vitamin D being well documented, researchers began exploring the possible negative side effects of not having enough vitamin D and found that those deficient in this micronutrient:

Are twice as likely to have a heart attack as men who had adequate levels of vitamin D 2

May be more likely to develop type 2 (possibly even type 1) diabetes as well as metabolic syndrome 5

Along with a CVD correlation, vitamin D levels may play a role in diabetes prevention and management.

Vitamin D & Diabetes

There are vitamin D receptors in almost all the cells in the body, suggesting vitamin D plays a role in most chemical processes but some of the more interesting roles in vitamin D include beta cell function and regulation– the cornerstone of diabetes.

Beta Cell Function & Insulin

The beta cells in the pancreas are responsible for producing and secreting insulin. In type 1 diabetes, the beta cells are destroyed by the body’s immune system and in type 2 diabetes, the beta cells attempt to over-produce insulin due to increasing insulin resistance caused by a variety of factors (lack of activity, excessive abdominal fat, genetics etc.).

Vitamin D, while still not completely definitive in relation to balancing glucose levels, is present in beta cells and may affect insulin production and secretion as insulin secretion is dependent on calcium (and calcium absorption is dependent on vitamin D). Some animal studies demonstrated removing vitamin D receptors, or creating a state of vitamin D deficiency, resulted in less insulin produced when needed and correcting vitamin D status restored proper insulin function. 6

Researchers have also noted a deficiency in vitamin D possibly related to decreased insulin sensitivity, which is seen prior to and post T2DM diagnosis. 7

Parathyroid Hormone & Insulin Resistance

Vitamin D deficiency has also been linked with an increase in parathyroid hormone, or hyperparathyroidism, which decreases insulin sensitivity as well.8

Note: bold arrows indicate firmly established cause and effect relationships and dotted arrows are relationships that are still in question

More and more evidence is showing vitamin D levels may be something to check and improve for overall health, improvement of diabetes management, and decreased risk of complications.

Preventing Diabetes With Vitamin D

A multitude of studies have explored the amount of vitamin D people get related to the incidence of T2DM.

A 2006 report from the Nurse’s Health Study, published in the journal Diabetes Care, followed over 80,000 women for 20 years. Women in the study who had both a calcium intake of more than 1,200 mg and a vitamin D intake of more than 800 IU had a 33% lower risk of developing Type 2 diabetes. 9

A 2011 study published in the European Journal of Clinical Nutrition found that a higher vitamin D intake decreased the risk of type 2 diabetes by 13% compared with a lower vitamin D intake. Individuals with the highest vitamin D status had a 43% lower risk of developing type 2 diabetes compared with those in the lowest group. 10

A 2013 study in Diabetes Care showed that higher vitamin D levels in mice were associated with decreased prevalence of T2DM. Specifically, each 10 nmol/L increment in vitamin D levels was associated with a 4% lower risk of type 2 diabetes. 11

While a variety of studies link the prevalence of T2DM to vitamin D deficiency and attempt to reduce prevalence through vitamin D supplementation, evidence is just not conclusive in asserting vitamin D can significantly reduce or prevent T2DM. Further, large-scale human trials need to be conducted to prove more significance.

Diabetes Complications & Vitamin D

The most common complication in patients with T2DM is cardiovascular disease, and research is approaching significance between vitamin D deficiency and markers for CVD.

Research up until 2017 as been very inconclusive: A wide variety of studies attempt to link vitamin D deficiency to diabetes (primarily T2DM) and cardiovascular disease, regarding vitamin D as a potential preventative or treatment measure for improved glucose homeostasis but lack the significance in their findings.

Multiple studies have drawn a correlation between vitamin D deficiency and insulin resistance while other studies have reported no significance or effect of vitamin D. Meta-analysis pooling over 50 studies in the last 40 years concluded the small sample sizes and predominant observational methods just don’t provide enough data to say concretely that vitamin D helps control glucose levels or prevent/reduce insulin resistance in T2DM’s.

Recently, at the Endocrine Society’s annual event, ENDO 2017, vitamin D deficiency was found to be significantly associated with an increase in LDL, or “bad cholesterol”, marking early cardiovascular disease and suggesting that vitamin D deficiency may have negative effects on health with increase in cardiovascular risk among individuals with low vitamin D concentrations. 12 This study highlights the role of monitoring vitamin D levels in children and adolescents who are overweight and obesity, and the potential benefits of improving vitamin D status to reduce the common cardiometabolic risk T2DM patients face.

Marisa Censani, M.D., a pediatric endocrinologist and director of the Pediatric Obesity Program in the Division of Pediatric Endocrinology at New York Presbyterian Hospital/Weill Cornell Medicine in New York, N.Y disclosed a significant connection between obesity as a risk factor for vitamin D deficiency:

“These findings suggest that vitamin D deficiency may have negative effects on specific lipid markers with an increase in cardiovascular risk among children and adolescents […] This research is newsworthy because this is one of the first studies to assess the relationship of vitamin D deficiency to both lipoprotein ratios and non-high density lipoprotein (non-HDL) cholesterol, specific lipid markers impacting cardiovascular risk during childhood, in children and adolescents with obesity.”

Vitamin D deficiency may be an important marker for cardiometabolic risk factors that often affect people with T2DM, and might become a regular screening tool in health as research continues.

Potential Downfalls in Vitamin D Research

Vitamin D deficiency is often seen in association with a higher BMI, high blood pressure, elevated triglycerides, and insulin resistance– all factors that commonly precede type 2 diabetes diagnosis. Vitamin D deficiency may very well be a significant factor in numerous conditions and diseases like T2DM but there are quite a few limitations in the research.

The findings from a majority of studies on vitamin D related to improved glucose homeostasis through insulin regulation are limited to very small sample sizes, usage of multiple different vitamin D compounds and dosing regimens, significant variance in protocols, and large collection of studies with null or negative findings.

There is a general lack of consistency in vitamin D intervention outcomes on insulin secretion and sensitivity.

In addition, the majority of studies investigating the association between vitamin D and insulin metabolism have used BMI, rather than a direct measure of body fat. The accuracy of BMI has been questioned for years. Many studies have not accounted for other factors linking vitamin D and insulin sensitivity, such as physical activity and calcium intake as well, which can be great ways to improve insulin sensitivity.

Ultimately, larger, randomized control trials need to be performed to definitively say there is a clear benefit of using vitamin D in terms of diabetes prevention and treatment.

Until then, taking vitamin D supplements within a healthy range and getting some sun exposure won’t hurt you and can possibly help you reduce risk for CVD as well as potentially improve insulin sensitivity, aiding in glucose regulation in people with type 2 diabetes. Researchers are enthusiastic about this cheap, safe, and effective solution that can hopefully make a big impact in the lives of diabetics.

If you have T2DM or even T1DM, talk to your doctor about checking your vitamin D levels and taking vitamin D supplements.

Disclaimer: Don’t take vitamin D in place of any medications you are currently prescribed. This article does not serve as medical advice and in no way is encouraging supplementation or a change in medical management self-practice unless directed by your doctor. Talk to your doctor regarding any changes you wish to make or questions you have regarding your health and diabetes management.

Chris Ruden has his bachelor’s degree in Exercise Science and Health Promotion and is an entrepreneur, model, and motivational speaker. Despite his congenital birth defect leaving him with only two fingers on his left hand and a shorter left arm, he is an Elite Powerlifter that has type 1 diabetes and works on an insulin pump. He has broken a number of state “powerlifting” records in Texas and Florida and he is showing the world that limitation are self-imposed!

Comments

I’ve tried every form (tablet, capsule, liquid – prescription and OTC) and my stomach rejects all of them. My doctor is very reluctant to give me the shots. Taste and texture wise I can’t tolerate and keep down the foods recommended so I will remain having low Vitamin D counts.

I take vitamin D in multivitamin gummies. Perhaps that will help. Another touted diabetes help is chromium. Like you, I’ve tried it in every form and my stomach rejects all of them. Some of us just cannot take every thing that’s out there, no matter how much is helps with diabetes..

I’d worry even more about why my stomach is so messed up that I couldn’t take vitamin D capsules. I’m not even sure what the heck would cause something like this. I’m guessing that there may be a psychological component here. Taking a vitamin D capsule should not produce any ill effects compared to capsules of something else.

A good article overall, but I want to mention that the Vitamin D Council does not suggest everyone can get optimal amounts of D with the sun, unless you live in tropical regions and spend a lot of time outdoors, like our ancestors did. The further from the equator you are the more you need to supplement, unless you do what Joe Mercola does and use a tanning bed. Tanning beds by the way aren’t anywhere near as bad as they lead you to believe, they just want us chronically deficient in this I think, stay out of the sun, and only take amounts far below what’s optimal.

Vitamin D does have a number of benefits for us but first and foremost it’s a nutrient that no one wants to be deficient in, for overall health if nothing else.

My wife read this and she suggested that it’s possible that someone might have an inflamed esophagus and gastritis bad enough to not be able to swallow capsules at all, in which case one would want to treat this, I would be taking things like glutamine, marshmallow root, and slippery elm for instance. She also wonders whether the patient has tried chewable gummies which should be well tolerated, or perhaps a spray, which is widely available. One thing is for sure, one does not want to ignore either the deficiency or the GI issues. If shots are the only alternative, they are regarded as safe and they actually don’t work as well as oral D does, but they are better than nothing for sure. One could always try some sun as well.

In practical experience it is found out that when D vitamin is supplied to the body through sunlight the sugar levels get controlled . Of course this is an observation and can’t be treated as a medical advice . Nevertheless when the vitamin is supplied through mild exposure to sunlight for a period of 20 minutes per day does not cause any grave injury and can be tried .